1. Field of the Invention
Generally, the present disclosure relates to the manufacturing of products, and, in particular, to the manufacturing of semiconductor devices by means of semiconductor tools.
2. Description of the Related Art
In the manufacturing of products having a relatively high degree of complexity, for example, semiconductor devices such as integrated circuits, a number of different manufacturing processes are performed by means of a plurality of tools. Examples of tools that can be used in the manufacturing of integrated circuits include steppers for performing photolithography processes, deposition tools for performing processes for the deposition of material layers on semiconductor structures, such as chemical vapor deposition reactors, plasma enhanced chemical vapor deposition reactors, apparatuses for performing physical vapor deposition, atomic layer deposition and/or spin coating, etching tools for performing etch processes, such as dry etching and wet etching, tools for performing processes such as oxidation, annealing and various cleaning processes, and metrology tools for monitoring manufacturing processes and for detecting defects of semiconductor devices in various stages of the manufacturing process.
In the manufacturing process, a number of workpieces, which, in the manufacturing of semiconductor devices typically include semiconductor wafers, each wafer including a number of semiconductor devices in a particular stage of a manufacturing process, may be combined into lots. The workpieces of a lot are processed in substantially the same manner, and typically by means of the same tools. For handling the lots, carriers can be used. The workpieces of a lot are inserted into a carrier for moving the workpieces between the tools that are employed for the manufacturing processes carried out at the workpieces of the lot.
For transporting the carriers, an automated material handling system may be employed, wherein the automated material handling system moves the carrier in an automated manner, for example, by means of vehicles and/or robots which are controlled by a computer system. The computer system can receive data from various tools, as well as from the automated material handling system, and can assign lots of workpieces to particular tools. The assignment of workpieces to tools can be performed on the basis of an availability of particular tools, constraints of the manufacturing process and priorities of the lots. Constraints of the manufacturing process can include maximum allowable queue times that should be observed to avoid adverse influences of long waiting times between some particular critical manufacturing processes on the quality of the manufactured products. Lots that should be processed more quickly, for example in view of delivery deadlines, can obtain a higher priority.
U.S. Pat. No. 5,980,183 discloses a system for the transport and storage of semiconductor wafers that can be used in the manufacturing of semiconductor devices. The system includes a plurality of storage locations that are provided along a wall of a tool bay containing process tools. Storage locations of the plurality of storage locations can be vertically aligned on top of each other. The system further includes a transport mechanism. The transport mechanism is capable of transporting a plurality of pods to and from each of the plurality of storage locations from above and/or from a side of the plurality of storage locations and to and from the plurality of process tools from above and/or from a side of the plurality of process tools without handoff of the plurality of pods during transport of the pods between the plurality of storage locations and between the plurality of storage locations and the plurality of process tools.
Conventionally, lots of workpieces can be assigned to a particular tool as soon as possible, for example as soon as a preceding processing step of a manufacturing process that is performed by another tool is completed. As soon as a lot of workpieces is assigned to a tool, the lot can be moved to the tool and included into a queue of lots that are to be processed by the tool. The lot stays in the queue until the tool is ready to process it. Following this strategy can lead to issues when lots of workpieces that are to be processed with a higher priority than lots that are already in the queue arrive. Reordering lots in the queue can require an undoing of actions taken on the current queue, for example transfers, or it can be associated with additional moves that are to be performed by the automated material handling system, and can be associated with a loss in throughput of the tool.
In view of the situation described above, the present disclosure provides methods, systems and data storage media that can help to substantially avoid or at least reduce some or all of the above-mentioned issues.